#ifndef _List_H

typedef int ElementType;

struct Node;
typedef struct Node *PrtToNode;
typedef PrtToNode List;
typedef PrtToNode Position;

List MakeEmpty(List L);
int IsEmpty(List L);
int IsLast(Position P, List L);
Position Find(ElementType X, List L);
void Delete(ElementType X, List L);
Position FindPervious(ElementType X, List L);
void Insert(ElementType X, List L, Position P);
void DeleteList(List L);
Position Header(List L);
Position Frist(List L);
Position Advance(Position P);
ElementType Retrieve(Position P);

#endif